WTB: 55# injectors
#16
Hey Man
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Originally Posted by 951Boost
I have a set of 55# Siemens with proper resistors. About 3K miles on them IIRC. I bought a used MAF that is set up for 72#'s so these need to go. $200 firm, PM if interested.
TIA
TIA
#18
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Originally Posted by 951Boost
I have a set of 55# Siemens with proper resistors. About 3K miles on them IIRC. I bought a used MAF that is set up for 72#'s so these need to go. $200 firm, PM if interested.
TIA
TIA
Originally Posted by Skip Wolfe
I have a set of 52# (550 cc/min) RC Engineering injectors - less than 500 miles on them. PM me if you are interested.
http://rceng.com/prices.htm
http://rceng.com/prices.htm
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#23
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BUMP: I knew this thread existed
Looks like everyone's injectors are sold! But I'm still interested in a source for resistors for the racetronix (or any) injectors.
These:
http://www.racetronix.com/3172FM.html
have a higher "coil resistance" than these:
http://www.racetronix.com/3102FM.html
is that what's required??
Looks like everyone's injectors are sold! But I'm still interested in a source for resistors for the racetronix (or any) injectors.
These:
http://www.racetronix.com/3172FM.html
have a higher "coil resistance" than these:
http://www.racetronix.com/3102FM.html
is that what's required??
#24
Three Wheelin'
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Originally Posted by porschefig
BUMP: I knew this thread existed
Looks like everyone's injectors are sold! But I'm still interested in a source for resistors for the racetronix (or any) injectors.
These:
http://www.racetronix.com/3172FM.html
have a higher "coil resistance" than these:
http://www.racetronix.com/3102FM.html
is that what's required??
Looks like everyone's injectors are sold! But I'm still interested in a source for resistors for the racetronix (or any) injectors.
These:
http://www.racetronix.com/3172FM.html
have a higher "coil resistance" than these:
http://www.racetronix.com/3102FM.html
is that what's required??
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#25
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http://www.fiveomotorsport.com/
Got mine there, very cheap. $250 is as I recall...is in the archives if you search for it.
Got mine there, very cheap. $250 is as I recall...is in the archives if you search for it.
#26
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[QUOTE=porschefig]But I'm still interested in a source for resistors for the racetronix (or any) injectors.
DigiKey link:
http://www.digikey.com/scripts/dksea...E-ND&x=15&y=11
Ohmite P/N 825F1R0E
DigiKey link:
http://www.digikey.com/scripts/dksea...E-ND&x=15&y=11
Ohmite P/N 825F1R0E
#27
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Originally Posted by Porschefile
Nope, definitely NOT! Sorry, not yelling at you.
I made this mistake with my Carrera and put the #3172 Siemens 55# injectors in when it really needed the #3102's, and I'd hate to see someone make the same mistake.
The #3172's have approximately 12ohms of resistance, which is MUCH more resistance than stock. I believe our stock 951 injectors are 5.5ohms resistance. Can someone confirm this? Please correct me if I'm wrong. The #3102's are listed as 2.35ohms, and it seems many low impedance injectors are roughly ~2-3ohms. 5.50ohm is definitely an odd resistance for most low impedance injectors and you need resistors to account for the other ~3ohms when going with some different aftermarket ones. I spent a lot of time speculating as to what kind of problems could be caused by having too much resistance, such as in the case of using the #3172's. All I know for sure is my Carrera still ran, but pretty F'ed up and it sure wasn't happy! Thankfully I have the proper #3102's in there now. ![hiha](https://rennlist.com/forums/graemlins/roflmao.gif)
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#28
Three Wheelin'
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Originally Posted by Geneqco
IIRC workshop manual says 3.5 to 5.5 ohms. I was told by at least a couple of suppliers that the low impedance 55s don't need resistors. Can you confirm either way? Did you use resistors in you Carrera. What's the benefit/consequence of using/not using resistors?
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#29
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Here is a post I made a while ago that looked at the reason for going with resistors:
All the injectors are driven by a single Darlington transistor and are connected in parallel. There are two wires going to the injectors to reduce voltage drop. The injector drive circuit turns on hard to set the injector solenoid, then it oscillates at a lower voltage to hold the injector open. This means the average current is less the*DC calculations, but you always will see the max current when the injector first turns on.
Resistance:
Stock == 4.5 ohms / 4 =1.225 Ohm
Other == 2.5 ohms / 4 =0.625 Ohms
Current:
(Voltage across injector is 10V due to driver loss)
Stock == 10 / 1.225 = 8.16 Amps
Other == 10 / 0.625 = 16.0 Amps
Now my cross to the driver transistor shows a max current rating of 16 amps. So, you are at the upper limit went you first turn on the injector. There also is a de-rating that should be applied for the heat generated by this transistor. At 16 amps, there is no more room for this de-rating.
So, if you run it hard, put a lot of heat into this transistor, it will be running above it max rating. If your transistor came from a good batch of transistors, they may take this. If you get a sub-normal batch, they may not.
All the injectors are driven by a single Darlington transistor and are connected in parallel. There are two wires going to the injectors to reduce voltage drop. The injector drive circuit turns on hard to set the injector solenoid, then it oscillates at a lower voltage to hold the injector open. This means the average current is less the*DC calculations, but you always will see the max current when the injector first turns on.
Resistance:
Stock == 4.5 ohms / 4 =1.225 Ohm
Other == 2.5 ohms / 4 =0.625 Ohms
Current:
(Voltage across injector is 10V due to driver loss)
Stock == 10 / 1.225 = 8.16 Amps
Other == 10 / 0.625 = 16.0 Amps
Now my cross to the driver transistor shows a max current rating of 16 amps. So, you are at the upper limit went you first turn on the injector. There also is a de-rating that should be applied for the heat generated by this transistor. At 16 amps, there is no more room for this de-rating.
So, if you run it hard, put a lot of heat into this transistor, it will be running above it max rating. If your transistor came from a good batch of transistors, they may take this. If you get a sub-normal batch, they may not.
Last edited by Bri Bro; 05-02-2007 at 08:14 PM.